The present invention relates to splicing apparatus for webs of flexible sheet material including paper, cardboard, imitation cork, metallic foil, plastic foil or the like. More particularly, the invention relates to improvements in apparatus for automatically splicing a running web to the leader of a fresh web while the running web is advanced at full or reduced speed or while the running web is arrested.
U.S. Pat. No. 3,030,043 discloses a splicing apparatus wherein the leader of a fresh web is held by a first positioning device at one side of the path for the running web while a second positioning device at the other side of the path is idle. The patented apparatus further comprises means for advancing the running web (i.e., for causing an expiring roll to pay out the running web) and two severing devices one of which is actuatable to sever the running web behind the splice immediately prior, during or subsequent to making of a splice between the running web and the leader of a fresh web. Still further, the patented apparatus comprises a splicer with two splicing sections which are movable, one at a time, to thereby attach the leader of the fresh web to the running web. Splicing apparatus of the just described character are used when the supply of fresh web forms a very large and bulky roll which is hard to handle, i.e., when the fresh roll is not shifted to the position previously occupied by an expired roll. Such apparatus are also preferred in machines where the space which is allotted for the splicing means is not sufficient to allow for shifting of rolls prior and/or subsequent to splicing. When a section of the splicer is set in motion, it causes the running and fresh webs to adhere to opposite sides of a uniting band both sides of which are coated with adhesive. The other section of the splicer serves as an anvil or back support which limits the extent of sidewise movement of webs with the moving section. The patented apparatus does not have any means for trimming the leader of a fresh web prior to splicing with the leader of a fresh web, and each section of the splicer receives motion from a discrete drive. Discrete drives for the sections of the splicer contribute to the cost and space requirements of the apparatus and necessitate the use of a complex control system if the splicing operation is to be carried out in automatic response to depletion of the supply of running web. The absence of trimming means can cause serious problems when the material of the webs is very sensitive, e.g., when the material is a thin metallic foil or a thin transparent plastic foil which is likely to wrinkle and/or undergo other types of deformation. In fact, it is practically impossible to thread the leader of a thin metallic or plastic foil through the apparatus without any wrinkling. If the deformed portions of the leader of a fresh web are not removed, the corresponding portions of the processed web must be detected and ejected from the machine which receives the running web. Typical examples of such machines are packing machines for cigarettes or the like wherein metallic foils are converted into blanks for the making of inner envelopes of cigarette packs and plastic foils are converted into transparent outer envelopes which are normally provided with customary tear strips. A pack having a defective (e.g., deformed) inner or outermost envelope must be segregated from other packs; this can entail substantial losses in output, especially in a modern packing machine which is designed to receive and process the output of one or more high-speed cigarette makers capable of turning out up to and in excess of 70 cigarettes per second.